270 ANNALS NEW YORK ACADEMY OF SCIENCES 



been noted: {a) increased readiness to enter the apparatus and to 

 desert it for the artificial burrow; {b) apparent "recognition" of the 

 artificial burrow which is used as "exit tube" ; (c) a gradual increase in 

 the number of avoidances of the sandpaper and of contact with the elec- 

 trodes as a. result of the "warning'^ influence of the sandpaper; (d) the 

 disappearance of the early tendency to retrace the path through the stem 

 of the T; (e) the similar disappearance of the tendency to turn back 

 after progressing well toward the exit tube. (6) The correct perform- 

 ance of a thoroughly ingrained habitual act, of the kind studied in this 

 investigation, is not dependent upon the "brain" (portions of the ner- 

 vous system carried by the five anterior segments ) , since the worm reacts 

 appropriately within a few hours after its removal. (7) As the brain 

 regenerates, the worm exhibits increased initiative, its behavior becomes 

 less automatic, more variable. (8) Within four weeks after the opera- 

 tion the regenerated segments appear superficially complete and the 

 worm naturally burro w^s in a mixture of earth and manure. (9) Two 

 months after the removal of the "brain," during the last four weeks of 

 which period no training was given, the habit had completely disappeared 

 from worm !N^o. 2, the subject to whose responses this paper is devoted, 

 and in its place there appeared a tendency to turn in the opposite direc- 

 tion to that demanded in the training. (10) Systematic training for 

 two weeks resulted in the partial reacquisition of the original direction- 

 habit. 



The general results which have just been stated are subject to modifi- 

 cation in the light of additional data. To the experimenter it seems that 

 the particular individual which has been longest under observation is in 

 many respects exceptional. It is perfectly clear, however, from results 

 obtained with other individuals that important modifications in behavior 

 appear as the result of training. It is equally certain that direction- 

 habits are not readily acquired. 



Dr. Watson's paper has been published in the PsychoJogical Review 

 for March, 1913. 



Professor Trowbridge classified the methods of orientation under two 

 heads. The first was called the domi-centric method, used by all living 

 creatures except man in a civilized state. In this case the manner of 

 moving about the surface of the earth relates to a point, usually the 

 home. In the second type, which -was called the ego-centric method, or 

 cardinal-point method, the use is made of the cardinal points of the com- 

 pass to give orientation, and those points do not necessarily relate to any 

 particular center or home. It is believed that those creatures using a 

 donii-centric method have an advantage over civilized man in finding 



